Complaint: Poor Customer Service- After Repair

I collected my vehicle after repairs on 12 November 2020, I noticed when I arrived home that the towing eye cover was missing, the cover was there when the car was towed on the day of the incident, I informed the Renew-it Bedfordview about the missing cover on the 13th, they advised me that they will investigate the matter and get back to me, I also informed my Insurance Discovery about this matter. I didn't get a call back from them for over a month and ended up buying the part myself from Mercedes. I called Renew-it Bedfordview's Operation Manager on 17th December, to follow up, I was informed that the part was ordered and sent back to spares, I don't know why it was sent back. Over a month of waiting for a callback, no one called about the part being ordered, and ready for fitment. I incurred the cost of replacing the part and the only thing they took care of was spray painting it and fitting it to my vehicle. They didn't refund me of the cost incurred for the replacement of the part which was their responsibility.